The microstructure and mechanical properties of as-cast Mg–4Y/Nd–2Zn alloys

ABSTRACT

Optical microscopy, scanning electron microscopy, X-ray diffraction and tensile testing were performed to investigate the microstructure and mechanical properties of as-cast Mg–4Y/Nd–2Zn alloys. The results show that the secondary dendritic arm spacing for the Mg–4Y–2Zn alloy is smaller than that for the Mg–4Nd–2Zn alloy, and that X-Mg₁₂YZn or W-Mg₃Zn₃Nd₂ form in Mg–4Y/Nd–2Zn alloys. The lamellar X phase distributes at the grain boundary, pointing into the grains, whereas the rod-like W phase preferentially segregates at the triangle junction of the grain boundary. The greater grain boundary strengthening effect and the smaller fragmentation effect of the brittle eutectic phases leads to the as-cast Mg–4Y–2Zn alloy having better comprehensive mechanical properties. The fracture mechanism for as-cast Mg–4Y/Nd–2Zn alloys is quasi-cleavage fracture.

KEYWORDS:

• Mg–4Y/Nd–2Zn alloys
• X phase
• W phase
• microstructure
• mechanical properties

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Key R&D Program of China [grant number 2016YFB0301002]; Jiangsu Science and Technology Achievement Transformation Project [grant number BA2016039]; Top Six Talent Project of Jiangsu Province [grant number 2014-XCL-005]; Suzhou Science and Technology Development Project [grant number SGC201534] and Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.